Coated article with sputter-deposited transparent conductive coating capable of surviving harsh environments, and method of making the same

ABSTRACT

Certain example embodiments relate to sputter-deposited transparent conductive coatings (TCCs) that are capable of surviving the harsh environments of ovens so that they can be included, for example, in oven door applications. In certain example embodiments, zirconium oxide (e.g., ZrO 2  or other suitable stoichiometry) may be used as a protective overcoat to protect an underlying Ag layer from corrosion in the atmosphere. In three lite oven door example embodiments, surface  1  has a TCC pyrolytically disposed thereon, surface  2  has a TCC sputter-deposited thereon and, optionally, surface  3  has a TCC sputter-deposited thereon. In two lite oven door example embodiments, surface  1  has a TCC pyrolytically disposed or sputter-deposited thereon, and surface  2  has a TCC sputter-deposited thereon.

FIELD OF THE INVENTION

Certain example embodiments of this invention relate tosputter-deposited coatings that are capable of withstanding harshenvironments, and/or methods of making the same. More particularly,certain example embodiments of this invention relate tosputter-deposited transparent conductive coatings (TCCs) that arecapable of surviving the harsh environments of ovens so that they can beincluded, for example, in oven door applications. In certain exampleembodiments, zirconium oxide (e.g., ZrO₂ or other suitablestoichiometry) may be used as a protective overcoat to protect anunderlying Ag layer from corrosion in the atmosphere.

BACKGROUND AND SUMMARY OF EXAMPLE EMBODIMENTS OF THE INVENTION

The use of transparent conductive coatings (TCCs) in high heat and harshenvironments such as, for example, oven door applications is known. See,for example, U.S. Pat. Nos. 6,320,164; 6,235,343; 6,024,084; and4,985,312, each of which is hereby incorporated herein by reference inits entirety. In general, a plurality of glass substrates inside theoven door helps absorb the heat generated in the interior of the ovenduring use and also helps reduce transmission of heat to the exteriorsurface of the oven door. In this regard, the TCC in an oven door helpsthe door to act as a heat barrier or heat sink. The ability for an ovendoor to act as a heat barrier or heat sink is needed in connection withself cleaning ovens, as the cook chamber of a self-cleaning oven mayreach temperatures as high as 600 degrees C. during the self-cleaningprocess. The exterior surface of the oven door cannot reach thistemperature and remain safe. For example, it is desirable to keep theexterior surface of an oven door below about 77 degrees C., morepreferably below about 60 degrees C., and more preferably still lower.

While efficacious for many known layer systems, the use ofsputter-coating has been known to result in mechanical durabilityqualities less than that achieved by known pyrolytic techniques. As areverse function, however, sputter-coated systems often achieve betterinfrared reflectance than typical pyrolytic coatings. Also,sputter-coated glasses have generally been recognized as having superioroptical and thermal performance characteristics than pyrolyticallyformed coatings, such as having improved coating uniformity, goodemittance, and better solar performance characteristics.

Unfortunately, only combustion vapor deposition (CVD) pyrolytic coatingshave been used for commercial oven door applications, since pyrolyticlayer systems are durable enough to withstand the harsh environments ofan oven including, for example, high temperatures, cleaning cycles,humidity, etc. However, it will be appreciated that if a sputter-coatingtechnique could be devised for a particular coating system wherein themechanical durability qualities of the sputter-coated system couldapproach or equal that of a pyrolytic technique, while at the same timeachieving the enhanced benefits of sputter-coated technology, asignificant step forward in the art would be made.

Thus, it will be appreciated that there is a need in the art forsputter-deposited layer systems that are capable of withstanding harshenvironments. It also will be appreciated that there is a need in theart for sputter-deposited transparent conductive coatings (TCCs) thatare capable of withstanding the harsh environments of ovens.

In certain example embodiments of this invention, a method of making adoor for an oven is provided. An inner glass substrate and an outerglass substrate are provided, with the inner glass substrate beingprovided for an interior side of the door and the outer glass substratebeing provided for an exterior side of the door. A first transparentconductive coating is disposed on a first surface of the inner glasssubstrate, with the first surface being farthest from the outer glasssubstrate. A second transparent conductive coating is sputter-depositedon a second surface of the inner glass substrate, with the secondsurface being closest to the outer glass substrate. The secondtransparent conductive coating includes a zirconium oxide protectiveovercoat. The inner and outer glass substrates are thermally tempered.

In certain example embodiments of this invention, an assembly used inthe creation of an oven door is provided. An inner glass substrate andan outer glass substrate are provided. A first transparent conductivecoating is supported by a first surface of the inner glass substrate,with the first surface being farthest from the outer glass substrate. Asecond sputter-deposited transparent conductive coating is supported bya second surface of the inner glass substrate, with the second surfacebeing closest to the outer glass substrate. The second transparentconductive coating comprises: a first barrier layer of silicon nitrideprovided on the second substrate, a first nickel chromium inclusivecontact layer provided on the first barrier layer, a silver-inclusiveconductive layer provided on the first contact layer, a second nickelchromium inclusive contact layer provided on the conductive layer, and asecond barrier layer of silicon nitride provided on the second contactlayer, and a zirconium oxide protective overcoat provided on the secondcontact layer.

According to certain example embodiments, the first transparentconductive coating is disposed on the first surface of the inner glasssubstrate via sputtering, and the first transparent conductive coatingincludes a zirconium oxide protective overcoat. According to certainother example embodiments, the first transparent conductive coating isdisposed on the first surface of the inner glass substrate viapyrolysis.

According to certain example embodiments, a middle glass substrate islocated between the inner glass substrate and the outer glass substrate,and the middle glass substrate is thermally tempered. According tocertain example embodiments, a third transparent conductive coating maybe sputter-deposited on a third surface of the middle glass substrate,with the third surface being farthest from the outer glass substrate,and with the third transparent conductive coating includes a zirconiumoxide protective overcoat.

The sputter-deposited transparent conductive coatings of certain exampleembodiments may comprise: a first barrier layer of silicon nitrideprovided on the substrate, a first nickel chromium inclusive contactlayer provided on the first barrier layer, a silver-inclusive conductivelayer provided on the first contact layer, a second nickel chromiuminclusive contact layer provided on the conductive layer, a secondbarrier layer of silicon nitride provided on the second contact layer,and a protective overcoat comprising zirconium oxide provided on thesecond barrier layer.

The example embodiments described herein may be used to build anassembly or intermediate product, which may be built into an oven door,and the oven door may be built into an oven.

In certain example embodiments of this invention, a method of making acoated article comprising a coating supported by a substrate isprovided. A transparent conductive coating is sputter-deposited on thesubstrate, with the transparent conductive coating comprising: a firstbarrier layer of silicon nitride provided on the substrate, a firstnickel chromium inclusive contact layer provided on the first barrierlayer, a silver-inclusive conductive layer provided on the first contactlayer, a second nickel chromium inclusive contact layer provided on theconductive layer, a second barrier layer of silicon nitride provided onthe second contact layer, and a protective overcoat comprising zirconiumoxide provided on the second barrier layer. One or more of these coatedarticles may be built into an assembly or intermediate product, whichmay be built into an oven door, and the oven door may be built into anoven.

In certain example embodiments of this invention, an assembly used inthe creation of an oven door is provided. An inner glass substrate andan outer glass substrate are provided. First and second middle glasssubstrates are provided between the inner and outer glass substrates.First, second, and third sputter-deposited transparent conductivecoatings are respectively supported by surfaces of the inner glasssubstrate, the first middle glass substrate, and the second middle glasssubstrate that face towards the outer glass substrate. The first,second, and third sputter-deposited transparent conductive coatings eachcomprise: a first barrier layer of silicon nitride provided on thesecond substrate, a first nickel chromium inclusive contact layerprovided on the first barrier layer, a silver-inclusive conductive layerprovided on the first contact layer, a second nickel chromium inclusivecontact layer provided on the conductive layer, a second barrier layerof silicon nitride provided on the second contact layer, and a zirconiumoxide protective overcoat provided on the second contact layer.

In certain example embodiments of this invention, an assembly used inthe creation of an oven door is provided. An inner glass substrate andan outer glass substrate are provided. First and second middle glasssubstrates are provided between the inner and outer glass substrates.First, second, and third transparent conductive coatings arerespectively supported by both surfaces of the inner glass substrate andan outer surface of the first middle glass substrate. The thirdtransparent conductive coating is a sputter-deposited transparentconductive coating. Either (a) the first transparent conductive coatingis a sputter-deposited transparent conductive coating and the secondtransparent conductive coating is a pyrolytically disposed transparentcoating, or (b) the second transparent conductive coating is asputter-deposited transparent conductive coating and the firsttransparent conductive coating is a pyrolytically disposed transparentcoating. Each said sputter-deposited transparent conductive coatingcomprises: a first barrier layer of silicon nitride provided on thesecond substrate, a first nickel chromium inclusive contact layerprovided on the first barrier layer, a silver-inclusive conductive layerprovided on the first contact layer, a second nickel chromium inclusivecontact layer provided on the conductive layer, a second barrier layerof silicon nitride provided on the second contact layer, and a zirconiumoxide protective overcoat provided on the second contact layer.

The features, aspects, advantages, and example embodiments describedherein may be combined to realize yet further embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and advantages will be better and morecompletely understood by reference to the following detailed descriptionof exemplary illustrative embodiments in conjunction with the drawings,of which:

FIG. 1 is a coated article supporting a first sputter-depositedtransparent conductive coating capable of surviving harsh environments,in accordance with an example embodiment;

FIG. 2 is a coated article supporting a second sputter-depositedtransparent conductive coating capable of surviving harsh environments,in accordance with an example embodiment;

FIG. 3 is an example oven and oven door incorporating at least the firstsputter-deposited transparent conductive coating of FIG. 1, inaccordance with an example embodiment; and

FIG. 4 is an example oven and oven door incorporating at least thesecond sputter-deposited transparent conductive coating of FIG. 2, inaccordance with an example embodiment;

FIG. 5 a is a flowchart showing an example process for creating the ovendoor of FIG. 3, in accordance with an example embodiment;

FIG. 5 b is a flowchart showing an example process for creating the ovendoor of FIG. 4, in accordance with an example embodiment; and

FIGS. 6 aand 6 b are example ovens and oven doors incorporating foursubstrates and sputter-deposited transparent conductive coatings, inaccordance with example embodiments.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS OF THE INVENTION

Certain example embodiments of this invention relate to transparentconductive coatings (TCC) that may be used in oven door applicationsand/or applications that where a TCC must withstand a great deal of heatand/or other harsh conditions. Certain example embodiments surprisinglyand unexpectedly enable sputter-deposited coatings to survive harshenvironments, such as those commonly encountered in self-cleaning ovencycles. Surprisingly and unexpectedly, zirconium oxide (ZrOx) may beused as a protective overcoat to protect an underlying Ag layer, e.g.,from corrosion in the atmosphere. In other words, the techniques ofcertain example embodiments help provide a more durablesputter-deposited coating.

The coatings described herein may be used in connection with a varietyof different embodiments. For example, the coatings described herein maybe used in connection with so-called two lite oven packs, three liteoven packs, etc. In certain example embodiments, the overall product maybe heated to a temperature up to about 600 degrees C. As will bedescribed in greater detail below, a pyrolytic coating optionally may beapplied to the non-sputter coated side of the glass substrate, and theproduct may be thermally tempered.

Certain example coated articles may be combined in a window pack withother clear or low-E coated lites, e.g., to manage the thermalcharacteristics of a window pack to keep the user-side surfacetemperature below regulatory requirements when the oven is in aself-cleaning cycle. A typical usage model for the window pack design isone that aims to achieve a user side surface temperature below 178degrees F. when the oven self-cleaning temperature reaches 850 degreesF. Of course, it will be appreciated that the performance demands on thewindow pack design may vary, for example, based on the actualcharacteristics of an oven design. Window packs containing uncoatedlites, single-sided coated lites and/or double-sided coated lites may becombined to achieve the most cost effective solution for targetedperformance characteristics. The coated lites described herein may beused in combination with, or as a substitute to, pyrolytic coatings. Thedetails of certain example configurations are provided below, althoughit will be appreciated that the same, similar, and/or otherconfigurations also may be present in certain example embodiments.

Referring now more particularly to the drawings in which like referencenumerals indicate like components throughout the several views, FIGS. 1and 2 show example coated articles including sputter-deposited TCCscapable of surviving harsh environments, in accordance with exampleembodiments of this invention. More particularly, FIG. 1 is a coatedarticle 1 supporting a first sputter-deposited transparent conductivecoating 2 capable of surviving harsh environments, in accordance with anexample embodiment, and FIG. 2 is a coated article 1 supporting a secondsputter-deposited transparent conductive coating 2′ capable of survivingharsh environments, in accordance with an example embodiment. Asexplained in greater detail below, in both TCC layer stacks 2 and 2′respectively shown in FIGS. 1 and 2, zirconium oxide (e.g., ZrO₂ orother suitable stoichiometry) is applied as a protective overcoat sothat a conductive layer (typically Ag) is protected from harshenvironmental conditions, with the conductive layer being sandwichedbetween first and second contact layers and first and second barrierlayers, such that the contact layers are provided between the conductivelayer and the barrier layers, and such that the zirconium oxide layer isthe outermost layer among at least these layers.

FIG. 1 includes a sputter-deposited TCC layer stack 2 supported by asubstrate 1. In the layer stack 2 of FIG. 1, a first barrier layer 3,which may include silicon nitride (e.g., Si₃N₄ or other suitablestoichiometry), for example, is provided on the substrate 1. A firstcontact layer 5, which may be a nickel-chromium inclusive layer (e.g.,NiCr or oxidized as NiCrOx), for example, is provided on the firstbarrier layer 3. A conductive layer 7 is provided on the first contactlayer 5, with the conductive layer 7 including Ag or any other suitableconductive material. A second contact layer 9 which, as above, may be anickel-chromium inclusive layer (e.g., NiCr or oxidized NiCrOx), forexample, is provided on the conductive layer 7. A second barrier layer11 which, as above, may include silicon nitride (e.g., Si₃N₄ or othersuitable stoichiometry), for example, is provided on the second contactlayer 9. A protective overcoat 13 of zirconium oxide (e.g., ZrO₂ orother suitable stoichiometry) is applied over the second barrier layer11, so as to protect the conductive layer 7 from the harsh environment.At least the first barrier layer 3 may be provided to a thicknesssufficient to reduce the likelihood of migration of sodium from theglass substrate 1 into the conductive layer 7, and at least the secondbarrier layer 11 may be provided to a thickness sufficient to reduce thelikelihood of migration of zirconium from the protective layer 13 intothe conductive layer 7.

FIG. 2 is a coated article 1 supporting a second sputter-depositedtransparent conductive coating 2′ capable of surviving high heats, inaccordance with an example embodiment. FIG. 2 is similar to FIG. 1, withthe exception that the TCC 2′ of FIG. 2 includes a conductive layer 7′that is different from the conductive layer 7 of the TCC 2 in FIG. 1.The conductive layer 7′ is thicker than the conductive layer 7, thusmaking the overall TCC 2′ more conductive than the TCC 2 of FIG. 1.

As can be seen, the thickness of the conductive layer 7′ in FIG. 2 isabout double that of the conductive layer 7 in FIG. 1. These differencesin thickness result in changes in conductivity of the overall coatings2′ and 2 and, thus, corresponding differences in sheet resistance. Inparticular, the FIG. 1 example results in a sheet resistance of about 15ohms/square, whereas the FIG. 2 example results in a sheet resistance of8 ohms/square. It will be appreciated that the amount of conductivematerial can be increased or decreased so as to affect the overall sheetresistance. For example, the inventors of the instant application havedetermined that the amount of Ag can be increased in certain exampleembodiments so as to reduce the sheet resistance to about 4 ohms/squarewithout significantly jeopardizing the Ag (e.g., as a result of cominginto contact with the harsh environment of an oven), provided that theoverall layer system is provided on the second surface of the lite pack(as shown, for example, in connection with FIG. 4 below). In general, asheet resistance of about 12-15 ohms/square can be obtained using theFIG. 1 example, or slight variations of the thickness in Ag thereof.

Example physical thicknesses (in nm) of the layers in thesputter-deposited TCC 2 and 2′ are provided in the table below:

FIG. 1 FIG. 2 Example Example Preferred More Preferred Layer (nm) (nm)Range (nm) Range (nm) ZrO₂ 10-20 10-20 1.5-50   10-20 Top Si₃N₄ 33.733.7 10-100 25-60 Top NiCr 2 2 1-10 1-5 Ag 6.1 12 2-20  3-12 Bottom NiCr2 2 1-10 1-5 Bottom Si₃N₄ 38.2 38.2 10-150 20-80

FIGS. 3 and 4 how example ovens and oven doors according to exampleembodiments of this invention. More particularly, FIG. 3 is an exampleoven 31 and oven door 32 incorporating at least the firstsputter-deposited transparent conductive coating 2 of FIG. 1, inaccordance with an example embodiment. The oven door 32 of FIG. 3 is aso-called three lite oven pack, in that it includes an innermost glasssubstrate 33, a middle glass substrate 35, and an outermost glasssubstrate 37. In certain example embodiments, the outermost glasssubstrate 37 may be a decorative lite. In certain example embodiments,the lites may have a common thickness (e.g., a thickness of 3.2 mm),although the lites need have the same thickness in all embodiments.

In the FIG. 3 example embodiment, a TCC 39 is applied to surface 1 ofthe lite pack 32 via a pyrolytic technique such as flame pyrolysis. Thetransparent conductive coating 2 of FIG. 1 is applied to surface 2 ofthe lite pack 32 via sputtering. Optionally, in certain exampleembodiments, the TCC 2 of FIG. 1 also may be sputter-deposited ontosurface 3 of the lite pack 32 in addition to being sputter-depositedonto surface 2 thereof. Also optionally, in certain example embodiments,the TCC 2 of FIG. 1 also may be sputter-deposited onto surface 4 of thelite pack 32.

The innermost glass substrate 33, middle glass substrate 35, andoutermost glass substrate 37 surprisingly and unexpectedly may be heattreated, even though sputter-deposited coatings are applied at least tothe innermost glass substrate 33 and optionally the middle glasssubstrate 35. For example, the innermost glass substrate 33, middleglass substrate 35, and outermost glass substrate 37 may be thermallytempered, e.g., at a temperature of at least about 580 degrees C., morepreferably at least about 600 degrees C. As noted above, conventionalsputter-deposited coatings cannot withstand this level of heat. Thus,the ability to thermally temper and to include such sputter-depositedcoatings in a product to be used in connection with an oven (where thetemperatures are high and where at least the self-cleaning conditionsare particularly harsh) is an advantage that is superior to conventionaltechniques that prohibit the use of sputter-deposited coatings in suchapplications.

FIG. 4 is an example oven 31 and oven door 32′ incorporating at leastthe second sputter-deposited transparent conductive coating 2′ of FIG.2, in accordance with an example embodiment. FIG. 4 is a so-called twolite oven pack and, thus, only includes an innermost glass substrate 33and an outermost glass substrate 37. As above, in certain exampleembodiments, the outermost glass substrate 37 may be a decorative liteand, in certain example embodiments, the lites may have a commonthickness (e.g., a thickness of 3.2 mm), although the lites need havethe same thickness in all embodiments.

Because there are only two lites in the lite pack 32′, additionalconductivity may be desirable for some or all of the TCCs disposed onthe substrates 33 and 37 thereof. Thus, in certain example embodiments,the TCC 2′ of FIG. 2 is sputter deposited on surface 2 of the lite pack32′. In general, TCCs similar to that of TCC 2′ of FIG. 2 may be used inconnection with the two lite pack 32′ of FIG. 4, so that the sheetresistance of the coating applied to surface 2 thereof is between about4-8 ohms/square.

In contrast to the lower sheet resistance of the TCC 2′sputter-deposited on surface 2 of the lite pack 32′, the surface 1 ofthe lite pack 32′ may have either (1) a pyrolytically disposed TCC 39applied thereto, or (2) the higher sheet resistance TCC 2 of FIG. 1sputter-deposited thereon. As above, the ability to thermally temper andto include such sputter-deposited coatings in a product to be used inconnection with an oven (where the temperatures are high and where atleast the self-cleaning conditions are harsh) is an advantage that issuperior to conventional techniques that prohibit the use ofsputter-deposited coatings. The pyrolytically disposed TCC 39 may have asheet resistance in certain example embodiments of about 12-15ohms/square.

FIG. 5 a is a flowchart showing an example process for creating the ovendoor of FIG. 3, in accordance with an example embodiment. Inner, middle,and outer glass substrates are provided in step S501. A first TCC ispyrolytically disposed (e.g., via CVD or the like) on a first surface ofthe inner glass substrate in step S503. In-step S505, a second TCC issputter-deposited on a second surface of the inner glass substrate. Instep S507, which is optional, a third TCC may be sputter-deposited on athird surface of the middle glass substrate. The inner, middle, andouter glass substrates are thermally tempered in step S509. In one ormore step(s) not shown, at least the inner, middle, and outer glasssubstrates may be built into an assembly in making the oven door and,furthermore, the oven door may be connected to an oven.

FIG. 5 b is a flowchart showing an example process for creating the ovendoor of FIG. 4, in accordance with an example embodiment. In step S511,inner and outer glass substrates are provided. In step S513, a first TCCis either sputter-deposited or pyrolytically disposed on a first surfaceof the inner glass substrate. A second TCC is sputter-deposited on asecond surface of the inner glass substrate in step S515. The inner andouter glass substrates are thermally tempered in step S517. In one ormore step(s) not shown, at least the inner and outer glass substratesmay be built into an assembly in making the oven door and, furthermore,the oven door may be connected to an oven.

In the example methods described in FIGS. 5 a and 5 b, thesputter-deposited TCCs may comprise, in order, a first barrier layer ofsilicon nitride provided closest to the respective substrate, a firstnickel chromium inclusive contact layer provided on the first barrierlayer, a silver-inclusive conductive layer provided on the first contactlayer, a second nickel chromium inclusive contact layer provided on theconductive layer, and a second barrier layer of silicon nitride providedon the second contact layer, with a protective overcoat (e.g., of orincluding zirconium oxide) being provided on the second contact layer.It will be appreciated that more or fewer layers may be provided incertain example embodiments and, thus, the various layers describedherein may directly or indirectly contact one another, depending on theparticular implementation. In general, a TCC layer provided on a surfaceof a substrate closest to the oven may have a higher sheet resistance,typically in the range of about 12-15 ohms/square, regardless of whetherthe TCC layer is sputter-deposited or pyrolytically disposed. Theremaining TCC layers may have sheet resistances of either 12-15ohms/square or 4-8 ohms/square, for example, depending on the particularimplementation chosen. As noted above, the amount of conductive materialin the layer stacks can be increased or decreased to reach the desiredlevel of conductivity/sheet resistance.

The pyrolytically deposited coatings of certain example embodiments maycomprise tin oxide. The pyrolytically deposited tin oxide coatings maybe doped with a dopant, for example, of fluorine. Example fluorine-dopedtin oxide coatings are described, for example, in U.S. Pat. Nos.4,601,917; 4,731,256; 4,731,462; 4,743,506; 4,775,552; 5,000,790;5,102,691; 5,725,904, the contents of each of which is herebyincorporated herein by reference in its entirety. Additionally, apyrolytically coated article commercially available from EGP andmarketed under the tradename HBI (Heat Barrier I) or HBII (Heat BarrierII) coating may be used in connection with certain example embodiments,as may a pyrolytically coated article commercially available fromPilkington marketed under the tradename TEC15.

Certain example embodiments have been described as relating to two-orthree-lite oven packs. However, more lites may be used in connectionwith certain example embodiments, wherein such lites may be coated oruncoated. For example, FIGS. 6 aand 6 b show example four lite ovenpacks. Both FIGS. 6 aand 6 b include innermost glass substrates 33,first and second middle glass substrates 35 a and 35 b, and outermostglass substrates 37 in their respective lite packs 62 and 62′. In FIG. 6a, the surfaces facing away from the oven on the innermost glasssubstrates 33 and the first and second middle glass substrates 35 a and35 b (surfaces 2, 4, and 6) are coated with TCC layer stacks 2 or 2′.

By contrast, in FIG. 6 b, one surface of the innermost substrate 33 hasTCC layer stacks 2 or 2′ applied thereto, whereas the other surface ofthe innermost substrate 33 has pyrolytically disposed TCC 39 appliedthereto. Thus, in certain example embodiments, when surface 1 has TCClayer stacks 2 or 2′ applied thereto, surface 2 has pyrolyticallydisposed TCC 39 applied thereto, and vice versa. The surface of thefirst middle substrate 35 a that faces away from the oven (surface 4)has TCC layer stacks 2 or 2′ applied thereto. Of course, it will beappreciated that other coating configurations may be used in connectionwith certain example embodiments.

Advantageously, the sputter-deposited TCC coatings of certain exampleembodiments may lead to better color uniformity and/or emissivitycharacteristics, at least as compared to current products that involvepyrolytic coatings only. Thus, the example embodiments described hereinmay be used in new applications and/or areas where a higher performanceand/or aesthetic appeal is necessary. Furthermore, the lower emissivitycharacteristics of certain example embodiments also may be used toimprove window pack performance and ultimately reduce OEM costs, e.g.,by reducing the number of lites required for the oven design.

Although certain example embodiments have been described in connectionwith low and/or high conductivity TCC layers, multiple TCC layers mayhave the same conductivity and/or sheet resistance. More over, the TCClayers may have sheet resistances of anywhere between about 4-15ohms/square. High conductivity layers may have sheet resistances at thelower end of this range (e.g., from about 4-8 ohms/square as describedabove), whereas low conductivity layers may have sheet resistances atthe upper end of the range (e.g., from about 12-15 ohms/square asdescribed above). Of course, the low and high conductivity TCC layersare not limited to these exact ranges. Moreover, TCC layers according toexample embodiments may fall within the example ranges above, regardlessof whether separate “high” and “low” conductivity layers or multiplelayers with the same or similar conductivities are implemented. Thus,for example, the layer stacks 2 in FIG. 3 may be replaced with layerstacks 2′ or other similar layer stacks with the same, similar, ordifferent conductivities and sheet resistances. Similar modificationsalso are possible to the FIG. 4 and FIGS. 6 aand 6 b exampleembodiments.

In certain example embodiments, the window packs may not be sealed. Insuch embodiments, the coatings may be designed so as to have a suitablyhigh durability to survive any harsh environments they encounter. Theinclusion of a zirconium oxide overcoat may help ensure such durabilityin certain example embodiments. In certain example embodiments, verticaland/or horizontal coating methods may be used to apply at least thepyrolytic coatings to the substrates.

Although certain example embodiments have been described as relating tooven door applications, it will be appreciated that the exampletechniques described herein may be applied to other applications. Forexample, the example techniques described herein may be applied to otherapplications where it is desirable to have a durable sputter-depositedcoating capable of surviving high temperatures and/or other harshconditions. Furthermore, the techniques of certain example embodimentsmay be applied to other electronics and/or appliance applications.

While a particular layer or coating may be said to be “on” or “supportedby” a surface or another coating (directly or indirectly), otherlayer(s) and/or coatings may be provided therebetween. Thus, forexample, a coating may be considered “on” and “supported by” a surfaceeven if other layer(s) are provided between layer(s) and the substrate.Moreover, certain layers or coatings may be removed in certainembodiments, while others may be added in other embodiments of thisinvention without departing from the overall spirit of certainembodiments of this invention. Thus, by way of example, an encapsulatingcoating applied in liquid sol-gel form in accordance with an exampleembodiment may be said to be “on” or “supported by” a sputtering targetmaterial, even though other coatings and/or layers may be providedbetween the sol-gel formed coating and the target material.

While the invention has been described in connection with what ispresently considered to be the most practical and preferred embodiment,it is to be understood that the invention is not to be limited to thedisclosed embodiment, but on the contrary, is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims.

1. A method of making a door for an oven, the method comprising:providing an inner glass substrate and an outer glass substrate, theinner glass substrate being provided for an interior side of the doorand the outer glass substrate being provided for an exterior side of thedoor; disposing a first transparent conductive coating on a firstsurface of the inner glass substrate, the first surface being farthestfrom the outer glass substrate; sputter-depositing a second transparentconductive coating on a second surface of the inner glass substrate, thesecond surface being closest to the outer glass substrate, wherein thesecond transparent conductive coating includes a zirconium oxideprotective overcoat; and thermally tempering the inner and outer glasssubstrates.
 2. The method of claim 1, wherein: the second transparentconductive coating comprises: a first barrier layer of silicon nitrideprovided on the second substrate, a first nickel chromium inclusivecontact layer provided on the first barrier layer, a silver-inclusiveconductive layer provided on the first contact layer, a second nickelchromium inclusive contact layer provided on the conductive layer, and asecond barrier layer of silicon nitride provided on the second contactlayer, and the protective overcoat is provided on the second contactlayer.
 3. The method of claim 2, wherein the first transparentconductive coating is disposed on the first surface of the inner glasssubstrate via pyrolysis.
 4. The method of claim 3, further comprising:providing a middle glass substrate located between the inner glasssubstrate and the outer glass substrate; and thermally tempering themiddle glass substrate.
 5. The method of claim 4, further comprisingsputter-depositing a third transparent conductive coating on a thirdsurface of the middle glass substrate, the third surface being farthestfrom the outer glass substrate, wherein the third transparent conductivecoating includes a zirconium oxide protective overcoat.
 6. The method ofclaim 5, wherein: the third transparent conductive coating comprises: afirst barrier layer of silicon nitride provided on the second substrate,a first nickel chromium inclusive contact layer provided on the firstbarrier layer, a silver-inclusive conductive layer provided on the firstcontact layer, a second nickel chromium inclusive contact layer providedon the conductive layer, and a second barrier layer of silicon nitrideprovided on the second contact layer, and the protective overcoat isprovided on the second contact layer.
 7. The method of claim 6, whereineach of the second and third transparent conductive coatings has a sheetresistance of 12-15 ohms/square.
 8. The method of claim 3, wherein thesecond transparent conductive coating has a sheet resistance of 4-8ohms/square.
 9. The method of claim 1, wherein the first transparentconductive coating is disposed on the first surface of the inner glasssubstrate via sputtering, and wherein the first transparent conductivecoating includes a zirconium oxide protective overcoat.
 10. The methodof claim 9, wherein: the first transparent conductive coating comprises:a first barrier layer of silicon nitride provided on the secondsubstrate, a first nickel chromium inclusive contact layer provided onthe first barrier layer, a silver-inclusive conductive layer provided onthe first contact layer, a second nickel chromium inclusive contactlayer provided on the conductive layer, and a second barrier layer ofsilicon nitride provided on the second contact layer, and the protectiveovercoat is provided on the second contact layer.
 11. The method ofclaim 10, wherein the first transparent conductive coating has a sheetresistance of 12-15 ohms/square, and wherein the second transparentconductive coating has a sheet resistance of 4-8 ohms/square.
 12. Themethod of claim 1, further comprising building at least the inner andouter glass substrates into an assembly in making the oven door.
 13. Amethod of making an oven, the method comprising: making an oven dooraccording to the method of claim 1; and connecting the oven door to theoven.
 14. A method of making a coated article comprising a coatingsupported by a substrate, the method comprising: providing thesubstrate; sputter-depositing a transparent conductive coating on thesubstrate, the transparent conductive coating comprising: a firstbarrier layer of silicon nitride provided on the substrate, a firstnickel chromium inclusive contact layer provided on the first barrierlayer, a silver-inclusive conductive layer provided on the first contactlayer, a second nickel chromium inclusive contact layer provided on theconductive layer, a second barrier layer of silicon nitride provided onthe second contact layer, and a protective overcoat comprising zirconiumoxide provided on the second barrier layer.
 15. The method of claim 14,further comprising tempering the substrate together with the transparentconductive coating.
 16. An assembly used in the creation of an ovendoor, comprising: an inner glass substrate and an outer glass substrate;a first transparent conductive coating supported by a first surface ofthe inner glass substrate, the first surface being farthest from theouter glass substrate; and a second sputter-deposited transparentconductive coating supported by a second surface of the inner glasssubstrate, the second surface being closest to the outer glasssubstrate, wherein the second transparent conductive coating comprises:a first barrier layer of silicon nitride provided on the secondsubstrate, a first nickel chromium inclusive contact layer provided onthe first barrier layer, a silver-inclusive conductive layer provided onthe first contact layer, a second nickel chromium inclusive contactlayer provided on the conductive layer, a second barrier layer ofsilicon nitride provided on the second contact layer, and a zirconiumoxide protective overcoat provided on the second contact layer.
 17. Theassembly of claim 16, wherein the first transparent conductive coatingis disposed on the first surface of the inner glass substrate viapyrolysis.
 18. The assembly of claim 17, further comprising: a middleglass substrate located between the inner glass substrate and the outerglass substrate.
 19. The assembly of claim 18, further comprising athird sputter-deposited transparent conductive coating on a thirdsurface of the middle glass substrate, the third surface being farthestfrom the outer glass substrate, wherein the third transparent conductivecoating comprises: a first barrier layer of silicon nitride provided onthe second substrate, a first nickel chromium inclusive contact layerprovided on the first barrier layer, a silver-inclusive conductive layerprovided on the first contact layer, a second nickel chromium inclusivecontact layer provided on the conductive layer, a second barrier layerof silicon nitride provided on the second contact layer, and a zirconiumoxide protective overcoat provided on the second contact layer.
 20. Theassembly of claim 19, wherein each of the second and third transparentconductive coatings has a sheet resistance of 12-15 ohms/square.
 21. Theassembly of claim 17, wherein the second transparent conductive coatinghas a sheet resistance of 4-8 ohms/square.
 22. The assembly of claim 17,wherein the first transparent conductive coating is a sputter-depositedcoating comprising: a first barrier layer of silicon nitride provided onthe second substrate, a first nickel chromium inclusive contact layerprovided on the first barrier layer, a silver-inclusive conductive layerprovided on the first contact layer, a second nickel chromium inclusivecontact layer provided on the conductive layer, a second barrier layerof silicon nitride provided on the second contact layer, and a zirconiumoxide protective overcoat provided on the second contact layer.
 23. Theassembly of claim 22, wherein the first transparent conductive coatinghas a sheet resistance of 12-15 ohms/square, and wherein the secondtransparent conductive coating has a sheet resistance of 4-8ohms/square.
 24. An assembly used in the creation of an oven door,comprising: an inner glass substrate; an outer glass substrate; firstand second middle glass substrates provided between the inner and outerglass substrates; and first, second, and third sputter-depositedtransparent conductive coatings respectively supported by surfaces ofthe inner glass substrate, the first middle glass substrate, and thesecond middle glass substrate that face towards the outer glasssubstrate, wherein the first, second, and third sputter-depositedtransparent conductive coatings each comprise: a first barrier layer ofsilicon nitride provided on the second substrate, a first nickelchromium inclusive contact layer provided on the first barrier layer, asilver-inclusive conductive layer provided on the first contact layer, asecond nickel chromium inclusive contact layer provided on theconductive layer, a second barrier layer of silicon nitride provided onthe second contact layer, and a zirconium oxide protective overcoatprovided on the second contact layer.
 25. An assembly used in thecreation of an oven door, comprising: an inner glass substrate; an outerglass substrate; first and second middle glass substrates providedbetween the inner and outer glass substrates; and first, second, andthird transparent conductive coatings respectively supported by bothsurfaces of the inner glass substrate and an outer surface of the firstmiddle glass substrate, wherein the third transparent conductive coatingis a sputter-deposited transparent conductive coating, wherein either(a) the first transparent conductive coating is a sputter-depositedtransparent conductive coating and the second transparent conductivecoating is a pyrolytically disposed transparent coating, or (b) thesecond transparent conductive coating is a sputter-deposited transparentconductive coating and the first transparent conductive coating is apyrolytically disposed transparent coating, and wherein each saidsputter-deposited transparent conductive coating comprises: a firstbarrier layer of silicon nitride provided on the second substrate, afirst nickel chromium inclusive contact layer provided on the firstbarrier layer, a silver-inclusive conductive layer provided on the firstcontact layer, a second nickel chromium inclusive contact layer providedon the conductive layer, a second barrier layer of silicon nitrideprovided on the second contact layer, and a zirconium oxide protectiveovercoat provided on the second contact layer.